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Hello, when trying to compile an small C program with uVision3 v3.53 I'm coming across some unexpected - at least to me - compilation errors, following is the complete program:
#include <reg515c.h> #define H 1 /* H abk. von HIGH */ #define L 0 /* L abk. von LOW */ sbit P4_0 = P4^0; main() { P4 = 0xFF; /* Port 4 als Eingang eingerichtet */ /*Why on earth these lines cannot be compiled?*/ unsigned char zustand = H; unsigned int i; while(1) { for(i = 0; i <= 8; i++) { while(P4_0 == H) ; if(P4_0 == L && zustand == H) { zustand = L; P1 = i; } while(P4_0 == L) ; if(P4_0 == H && zustand == L) { zustand = H; } } } }
And the error the compiler reports are: Build target 'mM-515' assembling STARTUP.A51... compiling PinNummern.c... PINNUMMERN.C(11): error C141: syntax error near 'unsigned' PINNUMMERN.C(11): error C202: 'zustand': undefined identifier PINNUMMERN.C(12): error C141: syntax error near 'unsigned' PINNUMMERN.C(12): error C202: 'i': undefined identifier PINNUMMERN.C(13): error C202: 'zustand': undefined identifier PINNUMMERN.C(18): error C202: 'i': undefined identifier PINNUMMERN.C(22): error C202: 'zustand': undefined identifier PINNUMMERN.C(24): error C202: 'zustand': undefined identifier PINNUMMERN.C(25): error C202: 'i': undefined identifier PINNUMMERN.C(29): error C202: 'zustand': undefined identifier PINNUMMERN.C(31): error C202: 'zustand': undefined identifier Target not created
The offending lines are the ones in red, neither the variable zustand nor i have sfr or sbit type so it should be allowed to declare them inside a function. When taking those variables out of main's body this way:
#include <reg515c.h> #define H 1 /* H abk. von HIGH */ #define L 0 /* L abk. von LOW */ sbit P4_0 = P4^0; unsigned char zustand = H; unsigned int i; main() { P4 = 0xFF; /* Port 4 als Eingang eingerichtet */ /* etc */
The program compiles without errors.
Any help would be appreciated. Thanks.
"That's a recipe for headaches."
Agreed!
But, even with better names, is there really any point in defining "HIGH" as 1 ?
Isn't that (nearly) as bad as:
#define ZERO 0 #define ONE 1
A more useful definition would be to give names that actually describe what the High and Low mean; eg,
#define LED_OFF 1 /* Writing a 1 (high) turns the LED off */ #define LED_ON 0 /* Writing a 0 (low) turns the LED on */
Then, if you change the "sense" of the drive, you only need to change the definitions - the usage of LED_ON and LED_OFF remain constant!
:-)
Well, it certainly is better than
#define Z 0 /* Abbreviation of ZERO */ #define O 1 /* Abbreviation of ONE */
... which would score major bonus points in the "unmaintainable code" category due to the similarity of 0 and O in some fonts.
Let's try to improve on the scores:
#define l 0 /* lit */ #define O 1 /* off */
The above looks more like a 2x2 identity matrix.
Zero isn't the only digit looking very similar to a letter :)